Background:Screening for COVID-19 infection in pediatrics is challenging as its clinical presentation may be asymptomatic or mimic other common childhood infections. We examined the use of a COVID-19 screening protocol (CSP) in the pediatric emergency department (PED) to determine the incidence of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) tests in patients who are CSP+ and CSP-.Methods: We conducted a retrospective cohort study of pediatric patients with SARS-CoV-2 testing completed in an urban tertiary care PED from November 1 to December 31, 2020. Demographics, CSP designation, test results, and disposition were compared. Statistical significance was determined using chi-square or a comparison of means. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) with 95% confidence intervals (CI) were calculated.Results: A total of 1,613 patients had SARS-CoV-2 tests completed with 9.1% (N=147) having positive test results. Of 1,014 (62.9%) patients who were CSP+, 12.9% tested positive. Comparatively, 599 (37.1%) patients were CSP- with only 2.7% positive tests, p<0.0001. The sensitivity, specificity, NPV, and PPV of the CSP in all tested patients were 89.1%, 39.8%, 97.3%, and 12.9%, respectively. Of tested patients, 887 (55.0%) were admitted to the hospital and were more likely to be positive if CSP+, p≤0.001. Within the admitted group, 16.8% were admitted to the operating room, of whom 83.9% were CSP- with 4.0% testing positive for SARS-CoV-2.Conclusions: COVID-19 screening in the pediatric population is a useful modality to risk stratify most patients presenting to the PED for the purpose of selective testing and guiding personal protective equipment use. This may be particularly useful in low-resource settings. The rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and the potential for severe illness associated with infection led the World Health Organization to declare the COVID-19 outbreak a global pandemic in March 2020 . EvidencCompared with the adult population, COVID-19 infection affects fewer pediatric patients; however, the number of cases of COVID-19 in children has been noted by the Centers for Disease Control and Prevention (CDC) to be rising since March 2020 . ChildreFever, rhinorrhea, cough, sore throat, nausea, vomiting, diarrhea, fatigue, myalgias, and headache have all been identified as presenting symptoms of COVID-19 in children ,11. SARSThe primary aim of this study was to evaluate the utility of COVID-19 screening in the pediatric emergency department (PED) by comparing the rate of positive SARS-CoV-2 tests in patients who screen “positive” with those who screen “negative” at ED triage. Secondary aims of the project include looking at the SARS-CoV-2 test positivity among COVID-19 screening protocol (CSP) positive (+) and CSP negative (-) groups within the subsets of patients admitted to the hospital, admitted to the operating room (OR), and discharged from the ED.Study designDuring the pandemic, the ED developed a database for the purpose of result follow-up and continuity of care for patients undergoing SARS-CoV-2 testing in the PED. This database was utilized to conduct a retrospective cohort study of pediatric patients with SARS-CoV-2 testing completed in the PED at an urban tertiary care children’s hospital in the United States with approximately 60,000 ED visits annually. The study population included patients ≤21 years of age with SARS-CoV-2 testing completed from November 1, 2020, to December 31, 2020. The study was approved by the institutional review board  and deemed exempt from consent due to the retrospective nature of the investigation. Standard protocols were utilized to assure that patient confidentiality was protected.ProcedureTo guide PPE usage and to cohort potential cases of COVID-19, the hospital independently made the decision to adopt the CSP in the PED during the pandemic. The hospital infection prevention committee designed screening questions to identify patients at high risk for potential SARS-CoV-2 infection. Screening questions were based on CDC guidance and information available through the state division of public health for essential services screening ,16. AlthQuestions were posed directly to the patient when developmentally appropriate. In instances when a child was not able to directly answer the CSP questions, the child’s caregiver served as a surrogate respondent, answering CSP questions based on their observation of the child’s symptoms. If the patient or accompanying caregiver answered “yes” to any of the above questions, the patient was deemed CSP+. Patients were designated CSP- only if answering “no” to all the above questions. Providers were informed of the patient’s CSP designation; patients received routine standard of care while in the ED. For patients deemed stable for discharge from the ED, the decision to obtain SARS-CoV-2 testing was made independently by the provider based on the patient’s symptoms and their potential COVID-19 exposures; this was largely guided by the patient’s CSP designation. All patients being admitted to the hospital or the OR received SARS-CoV-2 testing prior to admission.CSP questions were asked of all patients presenting to the ED during the study period. Due to testing limitations at the peak of the pandemic, SARS-CoV-2 testing was not able to be completed on all patients. Patients with SARS-CoV-2 testing completed as a requirement for hospital admission or at the discretion of the ED provider were ultimately included in the study. Patients over 21 years of age and those without SARS-CoV-2 testing were excluded. Regarding SARS-CoV-2 testing, four different tests were utilized: rapid polymerase chain reaction (PCR) (Xpert Xpress SARS-CoV-2/Flu/RSV), respiratory viral panel PCR (BioFire Respiratory Panel 2.1), standard immunology lab , and commercially available real-time reverse transcriptase (rRT) PCR testing. Data collection and data analysisPatients were identified retrospectively using the previously mentioned internal database. The CSP designation, SARS-CoV-2 test result, and disposition were recorded from this database. Demographic information including patient sex, age, race, and ethnicity was obtained from the hospital’s electronic data warehouse.Sample size calculation to power the main outcome of the study, sensitivity, and negative predictive values of CSP were performed using pilot data. Data were analyzed using SPSS v.27 . Descriptive statistics including means and standard deviations were calculated for continuous variables; counts and percentages were calculated for categorical variables. Statistical significance was determined using chi-square or a comparison of means where appropriate; statistical significance was determined to be p<0.05. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) with 95% confidence intervals (CIs) were calculated based on the construction of two-by-two tables for each patient cohort.During the study period, 5,937 patients were seen in our free-standing tertiary care PED, of whom 5,908 patients were ≤ 21 years of age. A total of 1,613 (27.3%) patients ≤ 21 years of age had SARS-CoV-2 testing completed and were included in the study sample. The demographics of the study population undergoing SARS-CoV-2 testing were similar to those presenting during the study period, although some statistically significant differences did exist  tested positive for SARS-CoV-2; their demographics are listed in Table Overall, 1,014 (62.9%) of tested patients were CSP+ with 131 (12.9%) of these patients ultimately testing positive for SARS-CoV-2. Comparatively, 599 (37.1%) patients were CSP- with only 16 (2.7%) positive tests for SARS-CoV-2 infection in the CSP- group. The test positivity rate between the CSP+ and CSP- groups was significant (p<0.0001). The sensitivity of the CSP was 89.1%, while the specificity of the test was only 39.8%. Two-sided 95% CIs for sensitivity and specificity are 82.9%-93.7% and 37.3%-42.3%, respectively. The NPV of the CSP was 97.3% (95% CI=95.8%-98.3%); however, the PPV of the screen was only 13.0% (95% CI=12.2%-13.7%)  were admitted to the hospital and 726 (45.0%) were discharged from the PED Figure . All patOf the 887 admitted individuals, 738 (83.2%) were admitted to the wards and 149 (16.8%) patients were directly admitted to the OR. Of the patients admitted to the OR, 83.9% (n=125) had negative COVID-19 screens with 4.0% (n=5) testing positive for SARS-CoV-2. There was no statistically significant difference (p=0.97) in positive SARS-CoV-2 test results in patients admitted to the OR with negative versus positive COVID-19 screens. In patients admitted directly to the OR, the sensitivity of the CSP was only 16.7% (95% CI=0.4%-64.1%), while the specificity of the CSP was 83.9% (95% CI=76.9%-89.5%). The NPV of the CSP patients admitted to the OR was 96.0% (95% CI=94.3%-97.2%); the PPV of the screen was only 4.2% (95% CI=0.7%-21.3%)  tested positive. In patients discharged from the ED, the sensitivity of the CSP was 97.2% (95% CI=92.1%-99.4%), while the specificity of the CSP was 7.4% (95% CI=5.5%-9.8%). The NPV of the CSP in discharged patients was 93.8% (95% CI=82.9%-98.0%); the PPV of the screen was 15.5% (95% CI=15.0%-16.0%) (Table This study demonstrates a significant difference in the rate of positive SARS-CoV-2 tests in patients screened for COVID-19 infection in the early phases of the pandemic. This statistical significance was demonstrated between the CSP+ and CSP- groups in patients admitted to the OR and discharged from the ED; the NPV of the screen was above 93% in both groups making a negative screen a reliable predictor of the absence of COVID-19 infection.At our institution, the CSP was initially used to enable patient cohorting and continues to be used to guide PPE precautions for healthcare workers. This is a method adopted by many free-standing children’s hospitals around the world at the start of the pandemic. Several international groups have published reports regarding adaptations made to the PED during the pandemic to cohort asymptomatic patients from those deemed high risk of potential SARS-CoV-2 infection ,4. HowevA study of adult patients presenting to an ED in Singapore revealed an 84.3% sensitivity of an internal screening protocol based on clinical symptoms and epidemiologic risk factors . Yet, scWhen comparing COVID-19 patient characteristics in Turkey, Akca et al. reported that 93.7% of pediatric patients with COVID-19 had positive household contact and 83.2% were symptomatic in the early months of the pandemic . SimilarYet, despite positive cases of COVID-19 detected in the CSP- group, this study does demonstrate a high NPV of the screen across all investigated groups. This is supported by the work of Roversi et al. who found that 99.3% of pediatric patients tested negative for SARS-CoV-2 when they had no reported exposure and no fever . In contGiven that this study was completed at one of the peaks of the pandemic, it was not possible to test all patients presenting to the ED due to resource limitations and the lack of clinical necessity. All patients admitted to the hospital received COVID-19 testing to ensure proper isolation precautions within the hospital system. This universal testing of admitted patients helps to eliminate a degree of selection bias and may be more reflective of the general population. When looking at the results for the subset of admitted patients, there is a significant difference in SARS-CoV-2 test positivity in patients admitted from the CSP+ versus the CSP- groups. This has important implications not only for patient cohorting and PPE guidance in the hospital setting but also for the outpatient setting where screening questionnaires are used routinely to risk stratify patients presenting to the office.This study highlights the importance of COVID testing prior to admission to the OR because the CSP was not able to significantly discriminate possible COVID-19 infection in this cohort. This is especially important given the invasive nature of surgical procedures and the greater potential for disease transmission in the OR . The lacRegarding the CSP, the cohort of patients discharged from the ED, the CSP was not able to discriminate SARS-CoV-2 test positivity in the CSP+ and CSP- groups. The study was not powered for this analysis making it difficult to make conclusions about this population at this time. Yet, the CSP did have a sensitivity of 97.2% in the discharged patient population suggesting that the use of a symptom- and exposure-based questionnaire may be useful to guide testing especially when resources are limited.As previously discussed, the possibility of selection bias is a limitation of this study. Except for patients being admitted to the hospital, the decision to obtain SARS-CoV-2 testing was at the discretion of the ED provider based on the patient’s symptoms and exposure history. It is likely that asymptomatic patients or those with atypical symptoms who were discharged were not captured in this analysis. This study is also limited by the inclusion of only patients with SARS-CoV-2 testing; diagnoses and CSP designations for patients without testing completed were not able to be examined in this analysis. Additional limitations include that the study was conducted at a single center and performed retrospectively. Furthermore, this study was completed in a tertiary care pediatric center making it difficult to generalize results to the adult patient population for use in the general ED. Additional prospective research with randomized testing of asymptomatic patients or universal testing of all patients is needed to evaluate this further. Currently, screening is only an adjunctive measure in the effort to mitigate the spread of COVID-19; testing remains the mainstay to identify true SARS-CoV-2 infections.This study was completed in the early phases of the pandemic, and ongoing research is needed to determine the efficacy of a CSP in the era of new SARS-CoV-2 variants. Additional studies are needed to understand the utility of COVID screening with the increased transmissibility of the SARS-CoV-2 Omicron variant -26. AddiA symptom- and exposure-based COVID screening protocol designed using CDC guidance for SARS-CoV-2 infection is a reliable tool to direct testing in the pediatric population. The CSP used in this study has a high NPV across all patient cohorts with a low probability of disease in those with negative screens; this is particularly useful to direct PPE practices in the healthcare setting and for infection prevention purposes. The negative predictive values of screening in the pediatric population support its use during the initial phases of the COVID-19 pandemic and may prove to be useful in the emergence of new strains. The use of screening protocols may be particularly valuable in areas with limited resources or the setting of testing scarcity; however, screening is not a replacement for the gold-standard PCR testing for the detection of SARS-CoV-2 infection.


The HRT group performed 3 sets and 10 repetitions twice a week using 80% of their baseline 1-RM (weeks 1–3), followed by 8 repetitions at 85% 1-RM (weeks 4–6), and 6 repetitions at 90% 1-RM (weeks 7–8) of 6 lower-body strength exercises with a 1 min rest period between sets. The PLY protocol involved a preparatory phase (weeks 1–2), followed by two 3-week progressive periods (weeks 3–5 and weeks 6–8). The plyometric sessions consisted of four jump exercises/drills with progressively increasing number of sets and total number of foot contacts. The rest intervals between repetitions and sets were 15 and 90 s, respectively. Outcome measures included tests assessing 10 and 30 m speed (t10m and t30m), one-repetition maximum half-back squat (1-RM squat), isokinetic peak torques for the quadriceps and hamstring muscles (Qcon and Hcon), countermovement jump (CMJ), and squat jump (SJ). Results: Two-way ANOVA detected main effects of time and group×time interactions for all examined variables, except t30m, 1-RM, and relative 1-RM. Post hoc analyses revealed significant increases in the HRT group  and the PLY group . HRT was superior compared to PLY in relative 1-RM, Qcon and Hcon . In addition, we found knee muscular strength imbalance in 70.5% of participants from the total sample (H/Q ratio < 60%). The HRT and PLY protocols resulted in improved neuromuscular functional performance compared to the regular soccer regime. Conclusions: This study showed that during the pre-competitive season, additional HRT and PLY drills/exercises as a substitute for standard soccer training as part of a regular 90 min practice twice a week for 8 weeks, can produce acute physical performance-enhancing effects in professional soccer players.Background: To compare the effects of short-term 8 week heavy-resistance or plyometric training protocols (HRT or PLY) incorporated into regular soccer practice on measures of neuromuscular functional performance in professional soccer players, a single-blind randomized controlled trial was conducted. Methods: Forty-seven participants aged 22.3 ± 3.52 years were assigned to three groups: HRT ( The comparative analyses of short-, medium-, and long-term effects of certain neuromuscular training methods  in the context of soccer-specific strength-based activities of professional athletes have been a key research topic in exercise science and physiology . AddressResistance training (RT) refers to specialized methods of physical conditioning and is considered a key strategy to improve neuromuscular function and subsequent on-field soccer performance ,5. ThereHeavy-resistance-training (HRT) elicits a plethora of adaptations on a structural and neural level and HRT programs utilize relatively high load/high force (>70% one repetition maximum (1-RM)) and thus lower velocity, relatively few repetitions (4–8 repetitions), and isoinertial exercises like the bench press or squat . From a The PLY training has been described as a sport-specific, effective, time-saving, and easy-to-implement training strategy in soccer players regardless of their age or competitive level ,22. ThisSeveral previous studies have been also inconclusive in determining the optimal design of PLY training  to promote increased muscle strength and power and improve match performance . PLY trTherefore, the aim of this study is to compare the effects of the addition of an 8-week pre-season HRT or PLY training protocol, in male professional soccer players, on neuromuscular functional performance measured by: running velocity, 1-RM half-back squat strength, peak concentric isokinetic knee extensor and flexor torques, and vertical jump performance. We hypothesized that neuromuscular functional performance would adapt differently depending on the training protocol used during the 8-week intervention. Specifically, we tested the hypothesis that incorporating high-impact unilateral and bilateral power/PLY exercises into standard soccer training would induce more substantial improvement in vertical jump performance than HRT, while HRT would provoke better effects in sprint, 1-RM half-back-squat strength and isokinetic peak torques for the quadriceps and hamstring muscles.2, body fat: 12.6 ± 3.31%, fat-free mass: 64.4 ± 5.02 kg) were recruited to participate in this study. The participants were recruited from the first Polish professional soccer league (3 different soccer clubs) and had 14.2 ± 1.54 years of experience in structured soccer-specific training. Exclusion criteria included: a history of (i) unresolved musculoskeletal disorders; (ii) lower-extremity reconstructive surgery in the last 2 years, or (iii) taking performance-enhancement drugs including anabolic steroids. Additionally, the participants from HRT and PLY groups were asked to cease any additional lower-limb RT for the entirety of this study to minimize the confounding effects.Forty-seven professional male soccer players , plyometric training group , and a control group . The randomization and blocking process resulted in the same number of goalkeepers (n = 2), defenders (n = 4), midfielders (n = 6), and forwards (n = 3) were present in the HRT and PLY groups, while 2 more forwards were in the CG group. Detailed subject characteristics are provided in In this single-blind randomized controlled design, participants were randomized into 3 groups after being blocked by tactical position. The three groups consisted of the following: heavy-resistance training group  and was performed in accordance with national standards in sport and exercise science research.−1 followed by 5 min of practice jumps, dynamic stretching of the lower limbs (no static stretching exercises), half-squat with low loads (two sets of five repetitions at 50% of body mass with 2 min of rest between sets), and 2 submaximal sprints of 20 m. The testing sessions were divided into 2 days, in the following order—day 1: SJ, CMJ, peak concentric isokinetic knee extensor and flexor torques; day 2: 10 and 30 m linear sprints and 1-RM half-back squat. Tests were separated by 10 min rest intervals. Testing venue, time of the day and order of tests were identical during testing sessions for all groups. Days 1 and 2 were separated by 48 h. All tests were performed in a fatigue-free state. After the intervention period, a follow-up (post-test) was performed under the same conditions as the baseline testing (pre-test). Baseline data were collected during the 1 week prior to the 8-week intervention. The post-test was conducted after the participants competed a 7-day taper, i.e., total training volume was reduced by 35%, and sessions included low-intensity soccer training contents only to maximize their individual strength-power performance  and sports hall. The participants were requested to maintain their diet and abstain prior to testing from caffeine and alcohol (minimum 24 h), avoid any strenuous exercise (minimum 48 h), and not use any non-prescription medication or supplements (minimum 48 h). All of the participants had experience in different modes of RT; all were accustomed to performing the 1-RM half-back squat, CMJ/SJ, and other resistive tests/exercises with correct technique, hence the potential learning effects were reduced. Nevertheless, prior to the testing session, the research manager provided participants with a full explanation of the study protocol, and participants were able to practice all tests in a familiarization session. The standardized warm-up period consisted of 5 min submaximal running at 9 km·hance see . Only paAnthropometry and body composition analysis included measuring standing body height with a stadiometer  and assessing body mass (BM), body mass index, percent body fat, and absolute fat-free mass with a MC-780U Multi Frequency Segmental Body Composition Analyzer  via bioelectric impedance analysis. All measurements were taken in the morning by a trained ISAK-accredited anthropometrist (Level 1) in compliance with the standard procedures recommended by the International Society for Advancement of Kinanthropometry.Test with a single-repetition limit (1-RM) was performed in accordance with a standardized protocol proposed by Chelly et al.  that was−1 (60°·s−1), each separated by 30 s rest period. The researcher provided verbal motivation during each trial to ensure maximal effort. The peak torque outputs were calculated in absolute Newton-meters (Nm) and in Newton-meters relative to body mass (Nm·kg−1 BM). The best performance of the three repetitions was used in the data analysis. Based on concentric hamstring and quadriceps peak torque values (Hcon and Qcon), H/Q peak torque ratios were calculated for each participant.Isokinetic peak torque for the knee flexors and extensors was performed on the dominant leg (designated as the preferred kicking leg). A standardized warm-up procedure including 5 min on a cycle ergometer and 5 min of static and dynamic stretches for the major lower limb muscle groups was completed prior to being positioned in a Biodex isokinetic dynamometer . The dynamometer set-up was completed following the manufacturer’s guidelines. Restraints were applied to secure the chest, hips, thigh, and distal femur. The lateral femoral epicondyle was aligned with the axis of rotation of the dynamometer and the knee was fixed at 90° of flexion. All actions were performed through a range of 0–90° knee flexion and extension (with 0° being full knee extension). The participant performed a series of practice trials at 50%, 75%, and 100% perceived maximal effort before performing three 3 s maximal voluntary concentric quadriceps and hamstrings actions, at an isokinetic angular velocity of 1.05 rad·smax) was determined as the center of mass displacement, calculated from the recorded force and BM. One minute of rest was allowed between the 3 trials of each test and the best (highest) trial was used for analysis. All jumps were performed on a tensometric platform and analyzed using specialized MVJ v.3.4 software .Vertical jump performance was measured with two different jump types: (i) SJ and (ii) CMJ. Following an individual 5 min warm-up  the participants began the SJ at a knee angle of 90°, avoiding any downward movement, and then performed an explosive vertical jump by pushing upwards, keeping their legs straight throughout. If a dipping movement of the hips was evident, then the trial was repeated. The CMJ was begun from an upright position, making a rapid downward movement to a 90° of knee flexion depth and simultaneously beginning to push-off. After each jump, the starting position was reset. An inter-repetition rest interval of 15 s was applied which is sufficient to fully recover vertical jumping ability and biomechanical-related parameters . Jump height (H−1) for 5 min followed by 3 min of dynamic stretching exercises. The participants were instructed to begin the test from a stationary start position, with their preferred foot placed forward 0.3 m behind the starting line. After 1 practice trial, the participants completed two trials separated by an interval of at least 5 min of slow walking and rest. Sprint time was measured using infrared photoelectric cells . A photocell was placed at the start, at 10 m, and 30 m. The times for the 10 m and 30 m sprint  were measured with an accuracy of 0.001 s using. The fastest trial was used for analysis.Running velocity was assessed on an indoor synthetic track and simultaneously tested for 10 m and 30 m sprint times. The test was preceded by a warm-up involving a low-intensity run , physical conditioning (3–4 sessions), and competitive control match (1 game per week), totaling approx. 18 h per week on average. Sunday served as a day of rest. Routine single training session ~2 h comprised 15–20 min warm-up, ~20 min of technical drills; ~30 min of tactical drills; ~20 min of small-sided games; ~30 min of simulated competitive games; and 10 min of cool down. All groups followed the described routine training program for the study period. The participants from intervention groups completed the HRT and PLY specific drills/exercises as a substitute for standard soccer training  within the scheduled 90 min practice sessions; two sessions per week over an 8-week period for a total of 16 sessions (Monday through Thursday). Previous studies have shown that this time period is long enough to elicit significant gains in physical performance in soccer players ,42. All The details of HRT program are displayed in Specific details of the PLY training protocol are presented in 2p) were used to determine the magnitude of the response to training protocols (effect size (ES) calculation with ∼0.01 = small effect, ∼0.06 = moderate effect, ≥0.14 = large effect). The p < 0.05 criterion was used for establishing statistical significance. The test–retest reliability  of performance assessments was determined using the Intra-Class Coefficients (ICCs) and Cronbach’s α. All statistical calculations were made using the STATISTICA™ v. 10.1 software package  and IBM SPSS Statistics for Windows, version 26.0.0.1 .The basic model of analysis was the analysis of variance system (ANOVA) with repeated measures (R) and a fixed factor, which was the group of subjects . The general test of analysis of variance of variables in repeated measurements is based on the assumptions of using MANOVA and Lambda–Wilks test, where each F-test tests the multivariate effect of pre- and post-factor. The assumption of normality of the distribution of the sampled data and the distribution of the differences of the measurements were tested using the Shapiro–Wilk test. In the case of the Qcon variables, the analysis of variance was performed on the data after a logarithmic transformation, which brought the distributions in the samples to distributions that conformed to the normal distribution. The homoscedasticity of the variance in the case of comparisons of variables at the time of measurement pre and post, between groups of subjects was verified by Bartlett’s test, and since it was not possible to assess the homoscedasticity of the variance in the case of repeated measurements, the result of analysis of the normality of the distribution of measurement differences was used as the result eligible for parametric testing, or an adjusted F value according to the lower limit of the epsilon measure was used. Testing the significance of differences between pairs of compared variables was performed with the HSD-Tukey test for samples of different sizes or the Tamhane T2 test in the situation of unequal variances or the absence of a normal distribution of the differences of pre- and post-measurements. For the variables: t30m, 1-RM, and relative 1-RM, the comparison of means between research groups for pre-test and post-test results was based on the Kruskal–Wallis test and post hoc Dunn test, and the comparison over time (pre/post) in each group was based on the Wilcoxon test. For the variables: t10m, CMJ, SJ, Qcon and relative Qcon, partial eta square values . In addition, CVs ranged from 1.1% to 2.5% .p < 0.05).The initial level of athletic performance between the research groups was comparable, as there were no significant differences at baseline in any of the variables tested  across the intervention period. The reasons for participants’ absence from training sessions were illness and/or mild musculoskeletal strains (mainly involving the lower extremities). None of the players received a serious injury during the intervention period.F = 16.162; p < 0.001; η2p = 0.429; (large ES)). Post hoc analyses revealed the greatest pre- to post-training decreases in t10m scores in the HRT group , and smaller in the PLY and CG groups . At post-test the sprint time in the HRT group was significantly faster (by 0.09 s or ∆4.6%) than in the CG group (Tukey test: p = < 0.001). The sprint time at 30 m (t30m) in the total study sample was significantly slower at pre- compared to post-test . The variation was significant in all groups . However, significant differences were present at the post-test  = 9.042, p = < 0.05), when the HRT group’s sprint time was significantly lower than the CG group’s   (r ∆3.4%) .height  = 30.274; p < 0.001; η2p = 0.585; (large ES)), and SJheight  = 113.791; p < 0.001; η2p = 0.841; (large ES)), respectively. Further post hoc tests showed a similar and significant pre- to post-training increases in CMJ and SJ height performances in all research groups , but with a greater within-group ES in HRT  when compared to PLY group   .p < 0.001, n = 46). The variation was significant in all groups . The average 1-RM showed significant differences between the groups at the post-test . In this time point, the 1-RM was significantly higher in the HRT compared to the CG group . In addition, pre- to post-training increase in 1-RM in HRT group was substantially greater compared to PLY group . For the entire sample analyzed, there was a significantly higher level in relative 1-RM at the post- compared to the pre-test , and the differences were significant in all groups . The average relative 1-RM variable did not differ between groups , while it differed between groups significantly at the post-test . As before, the HRT group’s score was significantly higher than that obtained by the CG group   .F = 15.247; p < 0.001; η2p = 0.415; (large ES)). Overall, the HRT group had a higher level of Qcon compared to the CG group (Tukey test: p = 0.003), Post hoc analyses also revealed significant increases in Qcon from pre-to post-training in the HRT  and PLY  groups without any significant changes in CG group (p > 0.05). Greater intra-group effect size was found for the HRT (ES = 0.424) when compared to either PLY or CG groups . At the post-test Qcon levels differed significantly between HRT and PLY groups ; and between HRT and CG . Moreover, a significant group × time interaction was observed for relative Qcon  = 25.061; p < 0.001; η2p = 0.538; (large ES)). In general, the HRT group had a higher level of the variable compared to the CG group (Tukey test: p = 0.003), while it did not differ from the PLY group (Tukey test: p = 0.314). There was also noted an improved post-training relative Qcon in the HRT (p < 0.001) and PLY (p < 0.001) groups   groups .F = 72.966; p < 0.001; η2p = 0.772; (large ES)). The post hoc tests revealed the greatest improvement from pre- to post-training in the HRT group . Considering the peak torque values relative to body mass (relative Hcon), there was again a significant group × time interaction  = 72.966; p < 0.001; η2p = 0.772; (large ES)). Post hoc analyses also revealed significant increases for the HRT and PLY groups in relative Hcon  (For the peak concentric isokinetic knee flexor torque (Hcon) a significant group × time interaction was noted (< 0.001) .p > 0.05) between PLY and CG groups for this measure at the pre-test , however CG group had significantly higher H/Q strength ratio (p < 0.05) compared to HRT group (Δ54.9%). In the post-test the significance level of between-group differences remained the same . Interestingly, from pre- to post-test H/Q strength ratios decreased in all groups . The percentage of soccer players who presented knee imbalance, characterized by lower values than 60%, is depicted in Regarding H/Q strength ratios for dominant knee there were no significant differences  improvements in the sprint performance were comparable following the HRT and PLY protocols, so both protocols can be performed twice a week for 8 weeks without negatively affecting sprint performance; the 1-RM half-back squat performance of the HRT group was substantially better compared to the PLY group, but only in relative terms; percentage increases from pre- to post-training in the Qcon and Hcon were almost two-fold greater in the HRT group compared to the PLY group; the majority of soccer players (70.5%) presented knee muscular strength imbalances, expressed by an H/Q ratio of less than 60%; and surprisingly, the high-impact PLY protocol was not more effective in increasing vertical jump performance compared to HRT.In several studies, 10 m and/or 30 m distances have been selected for sprint testing in soccer players ,47. In tr = 0.62, 0.78, 0.60, p < 0.001, respectively) and Comfort et al. [p < 0.05). In contrast, Requena et al. [However, as hypothesized, we expected better improvement in sprint performance in the HRT group, not PLY. We based our assumption on a systematic review and meta-analysis by Seitz et al.  showing t et al.  demonstrt et al.  demonstra et al.  found thheight, CMJheight, or 20 m sprint time with PLY training. Nevertheless, given the heterogeneous and multidimensional nature of sprint performance, perhaps the best option for improving linear and multidirectional sprint performance in the short term, in both youth and professional soccer players, is to adopt a combined RT and PLY program as part of the soccer regime [Previous observations suggest that HRT may differentially affect the initial acceleration phase (0–10 m) and the subsequent sprint interval  . Indeed,r regime ,64.p > 0.05), but in relative 1-RM there was a significantly higher score in favor of HRT (by 0.14 kg·kg–1 body mass (BM) or 13.4%, p < 0.05). Importantly, in the post-test 1-RM in the HRT group was 183.2 ± 18.9 kg and accounted the 244.6 ± 16.7% of their body mass (2.4 kg·kg–1 BM). Similarly, in the PLY group it was 168.9 ± 15.6 kg that represented the 230.7 ± 58.9% of their body mass (2.3 kg·kg–1 BM). The variation in this measure was comparable among the groups, and these short-term training responses could possibly induced transference effects, which in turn led to improved sprint times and vertical jump performance. However, these results were already expected for the HRT group, but such increments in 1-RM were actually surprising within the PLY group. Regarding the possible mechanisms, the positive changes in lower-extremity maximal strength might be related with improvements in neuromuscular function  that are likely to occur in response to high-impact PLY training [Since prerequisite levels of muscle strength are necessary to transfer velocity activities, it was formerly proven that the increases in 1-RM half-back squat values are responsible for running velocity improvements ,55,56. Itraining ,67.–1 BM) [–1 BM) [–1 BM) [–1 BM) [Moreover, the performance of both groups in absolute and relative 1-RM values in the half-back squat exercise was higher than the published data of Norwegian  , Polish  [–1 BM) , Estonia [–1 BM) , and Gre [–1 BM)  professi [–1 BM) ,69. Howe [–1 BM) , who sho [–1 BM)  who obseIsokinetic dynamometry is considered the gold standard for assessing muscle strength and imbalances between the knee flexors and extensors in soccer players . Isokine−1 (60°·s−1), and for tests performed at this angular velocity a reference value is close to 80% [−1), since angular velocity affects the isokinetic strength profiles of professional athletes, including soccer players [With reference to the literature, the average values of the conventional H/Q strength ratio range from 57–66% ,72,73, we to 80% . It is u players .Overall, in the current study, a pattern was observed in isokinetic contractions, in which HRT seemed to elicit greater increases in Qcon and Hcon after the training intervention, compared to the PLY and CON groups. In practice, soccer players with better scores in the bilateral isokinetic test would have an advantage when performing various muscle burst functions  using them during the game. This justifies the application of individualized pre- and in-season hamstrings strength programs. Unfortunately, the lack of implementation of effective hamstring strength protocols within the complex soccer training is a common problem in professional soccer.height: HRT = ∆5.9%; PLY = ∆3.3%; CG = ∆2.8%; SJheight: HRT = ∆7.2%; PLY = ∆3.5%; CG = ∆2.5%), but these improvements (in absolute and percentage terms) were two-fold greater with HRT than with the PLY protocol . It has been previously indicated that slow SSC jumps  are likely to benefit more from PLY training than concentric jumps  [De Villarreal et al.  suggeste.e., SJ) . HoweverIt is widely accepted that an athlete’s musculoskeletal system experiences extremely high impact forces during foot contact with the ground during high-intensity activity. In this study, multiple high-impact PLY exercises were performed as part of the PLY protocol . We speculated that muscle strength stimulation during each PLY session  would be highly effective for developing explosive strength (power) of the lower extremities. Moreover, given that the effectiveness of PLY depends on plethora factors, such as intermuscular coordination, muscle power, and biomechanical specificity, it was somewhat surprising that the PLY group was not superior in vertical jump performance compared to HRT. In this context, heavy general lower-extremity exercise such as the squat is relatively more effective in developing intramuscular coordination, whereas loaded and/or high-impact jumps are more effective in developing intermuscular coordination. Interestingly, improvements in explosive actions are revealed earlier following the RT than the PLY programs .height and SJheight observed in the HRT group were likely a result of maximal strength increases in the lower-extremity muscles . Resistance training focuses on the vertical component during triple extension of the lower body , as in various squat-type exercises , as these are considered more similar to explosive-type activities . However, we hypothesized that PLY-induced enhancements of explosive strength by improving motor unit synchronization, SSC efficiency, and/or muscle-tendon stiffness would elicit greater jumping performance in the PLY group. The increase in vertical jump scores observed in the HRT group may also explain the parallel increase in peak torques of knee flexor and extensor muscles in the current study , which were, as mentioned earlier, almost two-fold greater in the HRT group compared to the PLY group. Our results are consistent with related studies that have reported that Qcon and Hcon, assessed at slow speed and in concentric mode, showed correlations with SJ  [−1 angular velocity) and vertical jumping height [p < 0.05), and the five-jump test . However, the training load within this RT protocol was insufficient to significantly improve CMJ scores. Chelly et al. [Jumping height is a measure of performance that changes with alterations in 1-RM. Thus, the post-test scores and kinetics of CMJ< 0.001) . Interesg height . In addig height . The mecg height . Based og height , low-voly et al.  reportedy et al. , who obs−1) or in eccentric mode. We also did not measure morphological changes, such as quadriceps muscle cross-sectional area, or muscle pennation angle, which correlate well with maximal strength. Heavy-resistance training induces greater muscle fiber hypertrophy than other forms of physical training [There are some limitations to this study that need to be considered. The 8-week training intervention may not have revealed training adaptations that might have developed with longer programs (>10 weeks). In addition, this study did not include a combined HRT and PLY group, as has been done in some previous studies. A practical limitation is that due to daily variations in neuromuscular performance, the real 1-RM values for a given participant and exercise may change during a training intervention (from one training session to the next). Therefore, we cannot be sure that the workloads ) used in any particular training session fully match those intended and produced a certain training effect. It would also be advisable to monitor the repetition velocity loss during each resistance set to get an objective indicator of the actual degree of fatigue. Moreover, it was impossible to control all variables related to total training load, as well as many other confounding factors . Another limitation of this study was that we did not measure isokinetic peak torques at higher angular velocities . The outcomes of this study suggest that pre-season HRT is comparable to or more effective than PLY and CG in improving measures of sprint performance in both the acceleration (0–10 m) and maximal-velocity (0–30 m) phases (percent progress was greater in PLY), 1-RM half-back squat (but only in relative terms when compared to PLY), peak isokinetic torque of the knee extensors and flexors , and vertical jump performance (CMJ and SJ tests). The latter was rather unexpected, since the high-impact PLY protocol (range of 96–172 foot contacts during the 8-week intervention) included many vertical-type unloaded jump exercises very similar to the biomechanical structure of specific neuromuscular tasks like CMJ and SJ. The study showed some transference effects, such as between strength gains  and sprint performance over short and longer distances. From a practical standpoint, optimization of RT protocols should also match the soccer-specific technical skills of soccer players. Irrespective of the research group, an increased risk of sports injury  was found in more than 70% of soccer players (H/Q ratio < 60%). Based on this, coaches, strength and conditioning specialists, and medical staff should identify individuals with knee muscle imbalances, expressed as high quadriceps strength and low H/Q ratio, and apply individualized pre- and in-season hamstrings strength programs. Future longitudinal studies should determine what physiological/biochemical adaptations are responsible for the observed neuromuscular functional changes. The final and general conclusion is that during the pre-competitive season, additional HRT and PLY drills/exercises as a substitute for standard soccer training  as part of a regular 90 min practice twice a week for 8 weeks, can produce physical performance-enhancing effects in professional soccer players.


IntroductionAnterior Cervical Discectomy and Fusion (ACDF) is the gold standard treatment for symptomatic cervical spondylosis refractory to analgesic medical management. Currently, there are numerous approaches and devices used; however, there is no single implant that is preferred for this procedure. The aim of this study is to evaluate the radiological outcomes of ACDF procedures performed in the regional spinal surgery centre in Northern Ireland. The results of this study will aid surgical decision-making, specifically with regard to the choice of implant. The implants that will be assessed in this study are the stand-alone polyetheretherketone (PEEK) cage (Cage) and the Zero-profile augmented screw implant (Z-P).MethodsA total of 420 ACDF cases were reviewed retrospectively. Following exclusion and inclusion criteria, 233 cases were reviewed. In the Z-P group, there were 117 patients, with 116 in the Cage group. Radiographic assessment was carried out at the pre-operative stage, day one post-operation, and follow-up (> three months). Measured parameters included segmental disc height, segmental Cobb angle, and spondylolisthesis displacement distance.ResultsPatient characteristic features showed no significant difference between the two groups (p>0.05) and no significant difference in mean follow-up time (p=0.146). The Z-P implant was superior in increasing and maintaining disc height post-operatively  compared to the Cage  (p<0.001). Z-P was also more successful in restoring and maintaining cervical lordosis in comparison to the Cage group, as it had a significantly smaller kyphosis incidence (0.85% vs. 34.5%) at follow-up (p<0.001).ConclusionsResults of this study show a more advantageous outcome in the Zero-profile group as it restores and maintains both disc height and cervical lordosis; it is also more successful in treating spondylolisthesis. This study advocates cautious endorsement of the use of the Zero-profile implant in ACDF procedures for symptomatic cervical disc disease. Anterior cervical decompression and fusion (ACDF) is a widely recognised surgical option used to treat cervical spondylosis. Its basis is to restore normal anatomical structure by achieving increased disc height and stability of the vertebral column . The staIn Northern Ireland, both implants are routinely used for all ACDF procedures at the high-volume regional spinal surgery unit. Both implants are packed with demineralised bone matrix (DBM) to accelerate and ensure bone fusion. Due to the increased prevalence of dysphagia observed in anterior plating patients, this procedure is not performed at our centre for radiculopathic or myelopathic patients with cervical degenerative disc disease. The aim of this study is to evaluate radiographic outcomes in patients treated for cervical spondylosis through ACDF in Northern Ireland over the last five years. The results of this study will provide valuable insight into the biomechanics of the Cage and Z-P devices and help influence the choice of the most clinically advantageous implant for patients with cervical disc disease. This will help reduce post-operative complications and minimise the overall revision rate.Patients’ selection A total of 420 patients underwent 530 ACDF procedures for cervical spondylosis between April 2015 and December 2021. All procedures were performed on patients presenting with radiculopathy or myelopathy at the regional spinal surgery centre. Each operation was performed by a single surgeon, with a total of eight spinal orthopaedic surgeons across all cases. Retrospectively, all cases were reviewed, and their clinical and demographic information was recorded. Patients included in this study were: (I) treated using a Cage or Z-P device; (II) under 65 years of age at the date of operation; (III) date of operation within the last five years (April 2015-December 2021); (IV) ACDF performed at levels C3/4 to C7/T1. The exclusion criteria for this study were as follows: (I) trauma involved in the mechanism of injury; (II) pre-existing spinal deformity or disease ; (III) previous cervical spine surgical intervention; (IV) additional instrumentation ; (V) age at the date of operation greater than 65; (VI) follow-up period shorter than three months. After applying these criteria, a total of 233 patients were reviewed radiographically over a two-month period (June-July 2022).Surgical technique As per the records, an anterior Smith-Robinson approach was performed in all cases. The vertebral level was confirmed using C-arm fluoroscopy prior to disc intervention by the insertion of a Caspar distracting pin placed into the vertebral body above or below the level in question Figure .Vertebral body margins were prepared using a curette, and an additional distraction pin was inserted into the adjacent vertebral body into the diseased disc space. A Caspar cervical distractor was then used to restore natural disc height. The degenerative disc was removed using a combination of Kerrison rongeurs and pituitary forceps, decompressing the spinal cord or compressed nerve root. Osteophytes and remaining annular tissue were removed using a burr or Kerrison bone punch. The sizing of the implant was then performed using a template. The chosen implant was then inserted into the disc space, with its anterior border placed in line with the most anterior point of the vertebral bodies. In the Z-P group, locking screws were inserted under C-arm x-ray guidance at a 27°-44° angle in the cranial-caudal direction. Both Z-P and Cage devices were pre-packed with demineralised bone matrix (DBM) as per the standard procedure. After the insertion of each implant, intraoperative fluoroscopy images were taken to confirm cage positioning and ensure adequate alignment. The cages have titanium alloy markers anteriorly and posteriorly to aid location confirmation. The correct positioning of the Z-P spacer devices is indicated by all screws entering the middle of the vertebral body above and below. Haemostasis was performed when necessary, and incisions were closed with sutures by routine layer closure.Data collection Patient demographic and clinical characteristics were provided by the Fracture Outcomes Research Department (FORD) within the Royal Victoria Hospital, Belfast, Northern Ireland. Demographic and clinical dependent variables included age, sex, diagnosis, and the American Society of Anaesthesiologists (ASA) score. Other clinical variables, including level of operation, procedure, and implant used, were obtained from the Belfast Orthopaedic Information System (BOIS). Two imaging systems were used to obtain images for radiographic analysis: Sectra PACS  and Intellispace Portal 9.0 .Radiographic analysis Patients were reviewed using two imaging modalities: routine pre-operative whole spine magnetic resonance imaging (MRI) and cervical plain film radiographs with anteroposterior and erect lateral views. All patients were reviewed at three separate time periods: pre-operative (pre), post-operative (PO), and follow-up (FU). A pre-operative MRI was performed within three months of surgery. The post-operative x-rays were taken on day one post-surgery, and the follow-up was after three months. At this regional spinal centre, patients are routinely reviewed at three months and only reviewed after this time if they are symptomatic, have post-operative complications, or present with other spinal pathology . Numerous patients (44.6%) were further reviewed at six, 12 and 24 months, depending on disease severity. Vertebral disc height (DH) was measured at each time point to calculate segmental subsidence , as shown in Figure mm.ion of kyphosis at each time point. A kyphosis angle was classified as a positive value, while a lordosis angle was assigned a negative value. No calibration was required for both baseline MRI and lateral X-ray angle measurements. Following a study conducted by Kim et al. [Segmental Cobb angles (s-Cobb) were measured to evaluate the exacerbat2 m et al. , spondylInter-observer reliabilityAll images were reviewed by the author and two independent observers to measure inter-observer reliability and ensure measurements were accurate and consistent. Inter-observer reliability was determined for all three radiographic measurement types . Two independent observers were given a random sample of 35 patients, generated by a random number generator. Each patient had three images to be reviewed, for a total of 105 images analysed by each independent observer. This was then compared to the measurement taken by the author to obtain an intraclass correlation coefficient (ICC) for each measurement. This method was used as all data contained continuous numerical values. An ICC >0.90 indicated excellent reliability, with 0.75-0.90 being good, 0.5-0.75 being moderate, and <0.5 being poor. These reliability scores are based on guidelines suggested by Koo and Li .Statistical analysis Statistical analysis was performed using IBM Corp.'s Statistical Package for Social Sciences (SPSS 26.0) statistical software . All values were expressed as the mean ± standard deviation. Quantitative data were analysed using the Mann-Whitney U test, while qualitative data were evaluated using the Chi-square test. Statistical significance was considered when the p-value < 0.05. Linear graphs were also generated using the above software.Ethics Ethical approval or informed consent was not required for this study. The patient data acquired were kept anonymous in accordance with the Data Protection Act of 1998. Approval was provided by the Institutional Review Board within the Standards, Quality, and Audit Department at the Royal Victoria Hospital, Belfast, United Kingdom.Patient demographics The Cage group had 116 cases with a mean age of 45.0 (range 27-58). Fifty-five were male, while the remaining 61 cases were female. The most common vertebral level was C5/6 (53.0%). The next most common level of operation was C4/5, which occurred in 21.37% of this group. All patients were either ASA grade 1 or 2. The Z-P group consisted of 117 cases with a mean age of 46.2 years (range 20-60). Of this group, 58 were male and 59 were female. Most patients had few co-morbidities, with only two patients (1.71%) having an ASA grade of 3 and the remainder having either an ASA 1 or 2. The ASA 3 patients were so due to a diagnosis of hypertension with symptomatic coronary artery disease. Similar to the Cage group, the most common vertebral level of operation was C5/6, with a total of 59 patients (50.43%). This was followed by the C6/7 vertebral level (27.35%). There was no significant difference between the two population groups, as shown by the p-values in Table Inter-observer reliabilityThe mean ICC for all disc height measurements was 0.79, indicating good reliability. The ICC value for the measurement of s-Cobb was lower, with a value of 0.63, showing a moderate degree of inter-observer agreement. Spondylolisthesis measurements showed excellent inter-observer reliability, with an ICC of 0.91.Actual disc height (aDH) Mean aDH values are displayed in Table Segmental Cobb angle (S-Cobb)Both implants achieved the restoration of cervical lordosis immediately after surgical intervention Figure . The meaCompared to the post-operative measurements, there was a recurrence of kyphosis in both groups, as s-Cobb kyphosed by 2.6°±6.1 in the Cage group and 0.5°±2.3 in the Z-P cohort (p=0.009)  had significant spondylolisthesis pre-operatively, as defined by Tani et al. . IncidenSurgical management Symptomatic cervical disc disease presents with clinical syndromes such as myelopathy and radiculopathy. Failure to manage these symptoms by conservative means leads to the requirement of surgical intervention. The most common procedure performed on these patients is ACDF. This has historically provided successful arthrodesis and restored segmental stability. Since the 1980s, anterior plating has been common practice, improving the fusion rate and maintaining cervical lordosis in both single-level and multi-level cases ,6. HowevStudy demographics The demographic differences between the Cage and Z-P groups in this study were insignificant . The most common level of operation for both groups was C5/6. This goes against the most affected level for cervical spondylosis, which is C6/7 . This isComplications and revision A review of complications following ACDF procedures from 1989 to 2019 revealed a morbidity rate of 13.2%-19.3%. In this figure, the most common complication was post-operative dysphagia. Re-operation rates for these procedures range from 9.13% to 11.1% in single-level cases and 17.6% in multi-level cases -18. The This was followed by a revision of ACDF with the Z-P device. This patient was reviewed at the three-month and six-month follow-up stages. They were asymptomatic at both time points, and radiographs displayed restoration of cervical lordosis in addition to maintenance of disc height Figure .Change in intervertebral disc heightBoth implants were successful in increasing disc height immediately postoperatively; however, the Z-P group had significantly superior results at this stage (p = 0.001). This was also the case at follow-up, with the Cage showing a loss of disc height compared to the day one post-operative measurement (-0.7±0.67mm). The reason behind this is proposed to be due to increased focal stress on the cage, causing a loss of disc height ,21. DesRestoration of cervical lordosis Segmental Cobb angles were also evaluated, with both groups displaying restoration of cervical lordosis post-operatively. At follow-up, this lordosis reduced in both groups as time progressed; however, the Cage group demonstrated a significantly increased incidence of post-operative kyphosis (p<0.001). Segmental kyphosis has been linked to Cage use, with a mean loss in lordosis of 1.84° observed by Toni et al. . In thisSpondylolisthesis Degenerative cervical spondylolisthesis is not uncommon and has received an inadequate amount of attention. In this study alone, 18.9% had significant spondylolisthesis >2mm. Very few studies have measured the outcomes of ACDF procedures in degenerative spondylolisthesis patients. This current study measured it at each time point to compare the effectiveness of each implant in treating this condition. The Z-P implant was effective in both reducing the number of spondylolisthesis cases and their magnitude. However, this was not the case in the Cage group, as there was a recurrence of this condition in 68.2% of those who had it pre-operatively. This is likely due to the absence of a fixation mechanism in the Cage, therefore allowing anterior translation after repetitive flexion, extension, and axial loading ,26. FurImplant choice Evidence has demonstrated the benefit of using Z-P in comparison to conventional anterior plating due to the fixed-angle augmented screws providing a more rigid construct ,9. FurthClinical outcomes The main limitations of this study are, firstly, its retrospective nature, and secondly, the fact that clinical outcomes were not assessed. Despite the association between radiographic and clinical outcomes, it is not possible to draw that conclusion in this study. As there is an economic difference between the two devices, it would be worth correlating these results with the cost-effectiveness of using the Z-P implant. This is of particular interest as the majority of ACDF procedures performed in Northern Ireland are covered by the National Health Service (NHS).Overall, the regional spinal surgery centre in Northern Ireland produces satisfactory radiographic results for ACDF procedures. Compared to the Cage without screw augmentation, the Z-P augmented screw device proved more successful at reducing subsidence, maintaining cervical lordosis, and treating degenerative spondylolisthesis. These results are based entirely on radiographic outcomes. Clinical outcomes for patients treated with both implants need to be correlated with the radiographic results. Further research is required in the comparison between these two implants. A study combining an extended follow-up and the inclusion of clinical parameters would provide data that would aid clinical decision-making. This study, however, with consideration of patient characteristics, advocates a cautious endorsement for the use of the Z-P implant.


These devices exhibit bipolar RS with an intermediate resistance step during SET and RESET processes, which is believed to lie in the Si-NCs layer acting as charge-trapping nodes. The endurance studies of about 70 DC cycles indicate an ON/OFF ratio of ~106 and a retention time larger than 104 s. Long-term potentiation  and long-term depression  are obtained by applying consecutive identical pulse voltages of 150 ms duration. The current value gradually increases/decreases (LTP/LTD) as the pulse number increases. Three consecutive identical pulses of −2 V/150 ms (LTP) separated by 5 and 15 min show that the last current value obtained at the end of each pulse train is kept, confirming an analog RS behavior. These characteristics provide a possible way to mimic biological synapse functions for applications in neuromorphic computing in Si-NCs-based CMOS structures.In this work, we report the digital and analog resistive-switching (RS) characteristics in a memristor based on silicon nanocrystals (Si-NCs) integrated into a complementary metal-oxide-semiconductor (MOS) structure. Si-NCs with a diameter of 5.48 ± 1.24 nm embedded in a SiO Recently, SRO films containing Si-nanocrystals (Si-NCs) have been widely studied for application in RS devices [x with a SiOx:Ag layer, respectively [The conventional digital architecture based on the Von-Neumann architecture faces various challenges as computational complexity increases, due to the inefficient transfer of data between separated processing units and memories ,2. As a mristors ,18,19,20networks . Neverth devices ,23,24,25 devices . In thesectively ,28. Agaix-based nano-memristors, produced by a novel nanoembedding-and-oxidation-of-nanoparticles procedure, have shown a regeneration of RS properties after 1000 cycles by the application of a positive voltage higher than +15 V for 500 ms, which establishes again the condition for Si oxidation [2 multilayer (ML) structures [Pure SiOxidation ,30. At txidation ,32. In oructures . These d2/Si-NCs/SiO2 multilayer structure after thermal annealing. The digital RS indicates that these devices exhibit an ON/OFF ratio of ~106 and a retention time larger than 104 s. Meanwhile, the analog response of the memristor devices based on Si-NCs was analyzed by using identical voltage pulses. Compared to complex programming schemes, such as the variation of the voltage amplitude, pulse length, or current compliance, the use of identical pulses greatly reduces the complexity of the pulse-driving circuit, a critical requirement for their future application. Long-term potentiation  and long-term depression  are obtained by applying consecutive identical pulse voltages of 150 ms duration. Our results reveal a gradual change in electrical resistance for both the SET and RESET processes that can be controlled by the number of applied pulses.In this work, we introduce a Si-NCs-based memristor that exhibits both digital and analog switching, a property that has been seldom reported for this material. Si-NCs with a diameter of 5.48 ± 1.24 nm were formed in the SiO2/Si-NCs/SiO2 ML as RS material and deposited on a p-type (100) silicon substrate with a 1–5 Ωcm resistivity, with an Al electrode as the top contact, as schematized in 2/Si/SiO2 ML was deposited with an RF magnetron sputtering system by Torr InternationalTM. The ML process alternates the deposition of SiO2 and Si layers by the sputtering of pure SiO2 and Si targets in an argon plasma at 500 °C. The thickness of SiO2/Si/SiO2 layers was ~15 nm, ~6 nm and ~7 nm, respectively. The Si substrate was cleaned before deposition using an ultrasonic bath with acetone, ethanol, and deionized water, followed by submersion in an aqueous solution of hydrofluoric acid (HF). Then, after deposition, the MLs were thermally annealed at 1100 °C for 1 h under N2 atmosphere in a quartz tube furnace to promote the Si-NCs’ formation. The internal structure of the SiO2/Si-NCs/SiO2 ML system and successful formation of Si-NCs was confirmed by a high-resolution transmission electron microscopy (HRTEM) analysis using a microscope JEOLTM JEM 2200 . Aiming to analyze the electric behavior of the devices, an Al electrode was deposited over the SiO2 barrier layer using an electron beam evaporation (e-beam) system. The gate was defined by standard photolithography and lift-off processes with square patterns, with an area of 250 µm × 250 µm. Al Ohmic contacts were deposited on the back side of the substrates by electron beam evaporation at room temperature with a thickness of ~300 nm. Finally, the devices were thermally annealed at 460 °C for 20 min to improve the ohmic contact. The current-voltage (I-V) characteristics were measured using an Agilent Technologies B1500A semiconductor device parameter analyzer. Finally, for analog RS measurements, a B1525A high-voltage semiconductor pulse generator unit (HV-SPGU) installed on the B1500 was utilized. All experiments were performed in ambient conditions.MOS-like structures were fabricated using a SiO2/Si-NCs/SiO2 ML using a bright field detector (BF). As we can see, the ML structure allows for the formation of Si-NCs confined in the Si layer between the SiO2 layers. Moreover, the micrograph recorded with the BF detector reveals the successful formation of Si-NCs, which are evidenced by the marked different orientations of their atomic planes. The diameter of Si-NCs obtained in the ML structure is about 5.48 ± 1.24 nm.2/Si-NCs/SiO2 ML structure. Both devices show the same two-step forming process at forward bias , in which a first abrupt current step occurs at −6.15 V (continuous line), acting as an intermediate resistive switching (IRS) state, followed by a second step at −6.85 V. The first step (IRS) shows self-compliance, consistently stopping at around 20 nA across devices. For the second step, however, the current compliance (CC) is typically set at 100 μA to limit its maximum current. After the electroforming process, the devices show a bipolar resistive switching behavior, with a negative bias inducing the SET process (HRS to LRS) and a positive bias triggering the RESET process, returning to the HRS. Two kinds of RESET processes can occur: an abrupt RESET (continuous line) from LRS to HRS, and a step-wise RESET (dash-dot line), akin to the two-step SET discussed above. Multiple steps observed in the I-V curve represent different SETs before obtaining the highest current value reached in the devices, which is the partial formation of the conductive filament in the SiO2/Si-NCs/SiO2 ML structure. For the RESET process, one observes a voltage range  where the current increases (jumps) and decreases (drops), which is IRS (OFF). These effects can be related to a possible competition of the re-formation (jumps) and partial rupture (drops) until the complete annihilation of the conductive filament. Based on the conductive filament’s nature, if this is strong enough, it will require a higher energy to be destroyed, which is reached with a higher voltage and, in some cases, without the observation of the IRS . In fact, in a previous work, we reported a multilevel bipolar RS behavior in structures with eight Si-NCs/SiO2 bilayers [2 layers, which shows one intermediate state. This single intermediate level first corroborates the relation between the number of current steps and the Si-NCs layers, and second, it represents the partial formation/rupture of the conductive filament, connecting/disconnecting the Si-NCs layer with the neighboring SiO2 layers.bilayers . In thesbilayers ,35,36, wx-based devices have reported an endurance from 20 to 104 cycles with AC stimuli [−6 A and 1.32 × 10−12 A for all the I-V cycles, indicating an ON/OFF mean ratio of ~106, while a retention time larger than 104 s was measured in these devices , as shown in  stimuli ,23. As oices see d. ON/OFF devices ,23.2/Si-NCs/SiO2 structure, where Si-NCs act as charge trapping nodes, supporting the formation of conductive filaments to obtain the LRS. It is strongly possible that with subsequent measurement cycles, after the breakdown of the first (main) conductive filament, other new—and different—conductive paths are formed in the system, which are likely to branch out from the undamaged nodes of the initial conductive path. As these branches break down under voltage sweeps in consecutive measurement cycles, one expects that some Si-NCs will end up insolated or blocked from further participation in the conductive filament formation, changing their resistance and therefore the current value at LRS.As we can see in 2/Si-NCs/SiO2-based memristor device was analyzed with a pulse stimuli bias to observe its potential to mimic synaptic function. Potentiation and depression processes were achieved in these devices by applying a constant amplitude pulse train, as shown in The presence of different resistance levels is essential for the emulation of synaptic plasticity. For the analog synaptic device in neuromorphic computing, a gradual SET and RESET process is required to represent the synaptic weight value in artificial neural networks. Hence, the SiOIn summary, a memristor with digital and analog RS properties was proposed with the application of Si-NCs multilayer devices. These are promising first results due to the scarcity of similar studies in Si-NC devices in the literature. Additionally, thanks to the ability to stack a given number of layers, our devices have an extra degree of tuneability, allowing one to not only tailor parameters like the SET and RESET voltages but also to potentially adjust their analog behavior. Compelling future studies include a comparison of analog switching properties across devices with different numbers of Si-NC layers, as this could improve parameters such as the linearity of the analog switching process.


In modern, highly industrialized countries, endometrial cancer is the most common gynecological cancer. Endometrial cancer risk has been found to be influenced by a number of variables. The pathogenesis of endometrial cancer is heavily influenced by fatty food consumption in excess, a lack of physical activity and the subsequent development of obesity or diabetes. The first symptoms of endometrial cancer may be unusual vaginal bleeding or pelvic discomfort, but they are also typical of many other diseases. It is important to search for new biomarkers that could help detect endometrial cancer, even if it shows symptoms in its early stages. PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 are growth factor proteins. We investigated whether growth factor proteins can be clinically useful diagnostic markers in endometrial cancer. The study’s objective was to identify the clinical relevance of the proteins under investigation. We made a comparison between the serum protein concentrations of people with endometrial cancer and those with non-cancerous endometrial lesions.p = 0.0000; for EGF, p = 0.0186). The cut-off level of PDGF-AB was set at 127.69 pg/mL with a sensitivity of 87.1% and a specificity of 66.67% . The cut-off level of PDGF-BB was set at 207.86 ng/L with a sensitivity of 82.8% and a specificity of 75.76% . The cut-off level of TGF-α was set at 33.85 ng/L with a sensitivity of 82.8% and a specificity of 75.76% . The cut-off level of EGF was set at 934.76 pg/mL with a sensitivity of 83.87% and a specificity of 28.79% . The cut-off level of ANG-2 was set at 3120.68 pg/mL with a sensitivity of 72.04% and a specificity of 93.94% . (4) Conlusion: It was concluded that all the proteins studied could be potential diagnostic markers in endometrial cancer.(1) Background: It is relevant to find new diagnostic biomarkers for endometrial cancer. This study aimed to investigate whether PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 could be considered new useful markers for diagnosis and survival of endometrial cancer. (2) Methods: A total of 93 women diagnosed with endometrial cancer (EC) and 66 patients with non-cancerous endometrial lesions (NCEL) were included in this study. (3) Results: Median serum levels of PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 were significantly higher in the EC group compared to the NCEL group (for PDGF-AB, PDGF-BB, TGF-α and ANG-2,  In industrialized countries, endometrial cancer (EC) is the most prevalent gynecological cancer . While iPlatelet-derived growth factor (PDGF) is physiologically produced during platelet activation. PDGF has been shown to be a pro-angiogenic factor that plays an important regulatory influence on both normal and diseased blood vessels . There aEpidermal growth factor (EGF) plays a key role in cell differentiation and proliferation . The epiTransforming growth factor α (TGF-α) is a polypeptide that promotes cell proliferation and transformation . It is aAnother one of the key molecules involved in angiogenesis is angiopoietin 2 (ANG-2) . This moThe aim of this study was to determine the clinical significance of the proteins studied. Initially, we compared the serum concentrations of the proteins studied in patients with endometrial cancer (EC) and with non-cancerous endometrial lesion (NCEL). We then determined the correlations between the proteins studied. Finally, the importance of PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 in the diagnosis in endometrial cancer was evaluated. Since there are no relevant updated studies, this study will add to the knowledge on these proteins in endometrial cancer.This was an observational study. The study included patients treated for abnormal uterine bleeding. Transvaginal ultrasound was routinely performed in each patient. Patients with a thickened endometrium or suspected endometrial polyps on the transvaginal ultrasound were eligible for this study, and they subsequently underwent hysteroscopy and/or D and C (dilation and curettage). Patients with a histopathological diagnosis of endometrial cancer were then qualified for oncologic surgery. The study group with endometrial cancer and the control group without endometrial cancer were separated. The study group was further divided into subgroups according to histological subtype, grading and clinical stage (staging). Serum levels of the proteins studied were determined in both the study and control groups. Samples were collected between January 2015 and December 2018.The premenopausal group included patients with abnormal recurrent uterine bleeding and, on transvaginal ultrasound, a heterogeneous endometrium or shadowing that may correspond to an endometrial polyp . The postmenopausal group included patients whose endometrial thickness on transvaginal ultrasound was 5 mm (in patients not taking hormone replacement therapy) or 8 mm (in patients taking hormone replacement therapy). The exclusion criteria for the study were lack of patient consent, incomplete patient data, history of treatment for another cancer, pelvic inflammatory disease, histological diagnosis of uterine malignancy other than cancer, unbalanced chronic diseases and autoimmune diseases. Ultimately, 159 women were qualified for the study.2 (m2). Based on the results, the patients were sorted into two subgroups: with normal weight (BMI 18.5–24.9) and overweight and obese (BMI > 30). Moreover, each of the patients had a blood pressure measurement. Based on the results, we divided the patients into a group with (>140/90) and without hypertension. Moreover, based on the patients’ medical history, we assessed the presence of type 2 diabetes (DM2). The group characteristics are shown in At the beginning of the study, the patients’ body mass index (BMI) was measured based on the patients’ weight and height. The BMI was calculated based on the formula BMI = weight (kg)/heightThe preoperative serum PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 levels were determined using enzyme-linked immunosorbent assays  according to the manufacturer’s protocol. The specific steps were as follows: the standards of PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 were diluted to the corresponding concentration series and the samples and antibodies were added; 50 µL of Streptavidin-HRP was added to each well and incubated for 30 min; the chromogenic agent was used, and the samples were placed in the dark and incubated for 10 min at 37 °C before stop solution was added; the optical density (OD) value of each well at 450 nm was detected using a microplate reader.2 statistic (chi square) was used to assess the correlation between variables expressing protein concentrations and variables expressed on a nominal scale. A diagnostic test based on the ROC curve and, in particular, on the area under the ROC curve, which was determined using DeLong’s non-parametric method, was used to distinguish patients with the trait from patients without the trait.Statistical analysis was performed using Statistica 13.3.0 software. The following statistical methods were used to evaluate the collected research material: statistical description, correlation analysis and non-parametric Mann–Whitney U test of significance. A diagnostic test based on the ROC curve was also used. In the first step, statistical description was performed using arithmetic mean, median, minimum and maximum values and asymmetry coefficients. Since the distributions of the quantitative variables were not normal distributions, and the other variables were expressed on a nominal scale, a non-parametric significance test was used to compare the distributions: the Mann–Whitney U test. A nonparametric measure—Spearman’s rank-order correlation coefficient (test of significance for Spearman’s rank-order correlation coefficient)—was also used when testing correlations between quantitative variables. On the other hand, Pearson’s C contingency coefficient based on the χp = 0.0000; for EGF, p = 0.0186). The detailed data are shown in We initially determined the serum concentrations of the proteins studied in the EC and NCEL groups. We then compared the median concentrations of the groups. We found that median serum levels of PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 were significantly higher in the EC group compared to NCEL , PDGF-AB and TGF-α (r = 0.682), PDGF-AB and EGF (r = 0.226), PDGF-AB and ANG-2 (r = 0.473), PDGF-BB and TGF-α (r = 0.373), PDGF-BB and EGF (r = 0.226), PDGF-BB and ANG-2 (r = 0.574), TGF-α and EGF (r = 0.265), TGF-α and ANG-2 (r = 0.548), TGF-α and BMI (r = 0.179) and EGF and ANG-2 (r = 0.344). The detailed data are shown in In the next step, the correlations between the proteins studied were examined in the group containing premenopausal patients. A statistically significant positive correlation was found between PDGF-AB and PDGF-BB (r = 0.344), PDGF-AB and TGF-α (r = 0.704), PDGF-AB and ANG-2 (r = 0.587), PDGF-BB and TGF-α (r = 0.425), PDGF-BB and ANG-2 (r = 0.419), TGF-α and ANG-2 (r = 0.714) and EGF and ANG-2 (r = 0.31). The detailed data are shown in In the subsequent step, the correlations between the proteins studied were examined in the group containing postmenopausal patients. A statistically significant positive correlation was found between PDGF-AB and PDGF-BB (r = 0.23), PDGF-AB and TGF-α (r = 0.671), PDGF-AB and EGF (r = 0.225), PDGF-AB and ANG-2 (r = 0.428), PDGF-BB and TGF-α (r = 0.356), PDGF-BB and EGF (r = 0.241), PDGF-BB and ANG-2 (r = 0.63), TGF-α and EGF (r = 0.264), TGF-α and ANG-2 (r = 0.47) and EGF and ANG-2 (r = 0.358). The detailed data are shown in p < 0.000001). The cut-off level of PDGF-BB was set at 207.86 ng/L with a sensitivity of 82.8% and a specificity of 75.76% . The cut-off level of TGF-α was set at 33.85 ng/L with a sensitivity of 82.8% and a specificity of 75.76% . The cut-off level of EGF was set at 934.76 pg/mL with a sensitivity of 83.87% and a specificity of 28.79% . The cut-off level of ANG-2 was set at 3120.68 pg/mL with a sensitivity of 72.04% and a specificity of 93.94% . The detailed data are shown in The diagnostic significance of the tested proteins was evaluated between the study group (EC) and the control group (NCEL). The cut-off level of PDGF-AB was set at 127.69 pg/mL with a sensitivity of 87.1% and a specificity of 66.67% . The cut-off level of PDGF-BB was set at 197.79 ng/L with a sensitivity of 94.12% and a specificity of 55.56% . The cut-off level of TGF-α was set at 34.71 ng/L with a sensitivity of 82.35% and a specificity of 94.44% . The cut-off level of EGF was set at 934.76 pg/mL with a sensitivity of 91.18% and a specificity of 33.33% . The cut-off level of ANG-2 was set at 3132.47 pg/mL with a sensitivity of 73.53% and a specificity of 94.44% . The detailed data are shown in The diagnostic significance of the tested proteins was evaluated between the study group (EC) and the control group (NCEL) in premenopausal patients. The cut-off level of PDGF-AB was set at 106.66 pg/mL with a sensitivity of 94.12% and a specificity of 61.11% . The cut-off level of PDGF-BB was set at 207.86 ng/L with a sensitivity of 86.44% and a specificity of 77.08% . The cut-off level of TGF-α was set at 33.85 ng/L with a sensitivity of 83.05% and a specificity of 68.75% . The cut-off level of EGF was set at 1231.72 pg/mL with a sensitivity of 52.54% and a specificity of 72.92% . The cut-off level of ANG-2 was set at 3120.68 pg/mL with a sensitivity of 71.19% and a specificity of 93.75% . The detailed data are shown in The diagnostic significance of the tested proteins was evaluated between the study group (EC) and the control group (NCEL) in postmenopausal patients. The cut-off level of PDGF-AB was set at 130.26 pg/mL with a sensitivity of 86.44% and a specificity of 64.58% (AUC = 0.76, Although endometrial cancer is one of the most common gynecological cancers and its morbidity rate is increasing, it is still not yet as investigated as ovarian or cervical cancer. There is currently no biomarker that is used for diagnostic purposes in endometrial cancer, but that is the reason why it is so important to keep conducting research. Our study was conducted to answer the question if PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 could be useful as markers to diagnose patients with endometrial cancer. According to the results, the median serum levels of PDGF-AB, PDGF-BB, TGF-α, EGF and ANG-2 were significantly higher in the group of patients that suffered from EC compared to patients with NCEL. There seemed to be an association between the serum concentrations of the proteins tested in our study. One of the limitations of our study was the small number of patients in both the study and control groups. Another limitation was that the control group consisted of both patients who had endometrial polyps and patients who had a thickened endometrium. However, this was due to the division into patients having non-cancerous lesions, which included endometrial polyps and thickened endometrium, and those with cancerous lesions. In this way, we clearly delineated the study group and the control group.PDGF has been shown to be a pro-angiogenic factor, but not many studies have considered its dimer subtypes. In the literature, we can find references to other types of cancers than the one tested during our study, such as ovarian cancer ,19, breaAttention to biomarker concentrations and their changes with cancer treatment also seems to be an important topic. The literature provides general information on changes in PDGF levels in surgically treated colorectal cancer  and in tAmong premenopausal women, the incidence of endometrial cancer is in the range of about 14–20% , also inThe results of the presented research seem promising. However, attention should be paid to the use of proteins in the diagnosis of EC without and with consideration of menopausal status. Particularly relevant is the use of the EGF protein in the diagnosis of EC in a group of premenopausal patients, in which a non-significant result was obtained here. In light of currently available studies, it is difficult to explain this result, especially since this protein is similar in function to the other proteins studied here. The diagnostic utility of this protein in a group of postmenopausal patients should also be interpreted with great caution, as the sensitivity is 52.54%—a significantly lower sensitivity compared to the other proteins. The other proteins show significantly similar sensitivity and specificity in both premenopausal and postmenopausal patients.As we mentioned earlier, the data collected during our study are limited by the size of our study group. For a confirmation of the results, it would be necessary to conduct a similar study again in the future, but with a larger group of patients. The data gathered in the literature confirm that the elevated serum concentration levels of proteins tested in our study are found in many other carcinomas apart from endometrial cancer. These results suggest that all of the proteins studied could be potential biomarkers in the diagnosis of endometrial cancer. However, taking into account the menopausal status of the patients, in the group of premenopausal patients, PDGF-AB, PDGF-BB, TGF-α and ANG-2 could be potential biomarkers for the diagnosis of endometrial cancer. In the group of postmenopausal patients, as in the total cohort, all the proteins tested could be markers of endometrial cancer. In order to confirm the results, it would be necessary to conduct a similar study again, especially involving a larger group of female patients.